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skmsg: Move sk_redir from TCP_SKB_CB to skb

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Currently TCP_SKB_CB() is hard-coded in skmsg code, it certainly
does not work for any other non-TCP protocols. We can move them to
skb ext, but it introduces a memory allocation on fast path.

Fortunately, we only need to a word-size to store all the information,
because the flags actually only contains 1 bit so can be just packed
into the lowest bit of the "pointer", which is stored as unsigned
long.

Inside struct sk_buff, '_skb_refdst' can be reused because skb dst is
no longer needed after ->sk_data_ready() so we can just drop it.

Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20210223184934.6054-5-xiyou.wangcong@gmail.com
This commit is contained in:
Cong Wang 2021-02-23 10:49:29 -08:00 • committed by Alexei Starovoitov
parent 16137b09a6
commit e3526bb92a
5 changed files with 62 additions and 37 deletions
Download patch file Download diff file Expand all files Collapse all files

8
net/core/sock_map.c
View file

@ -657,7 +657,6 @@ const struct bpf_func_proto bpf_sock_map_update_proto = {
BPF_CALL_4(bpf_sk_redirect_map, struct sk_buff *, skb,
struct bpf_map *, map, u32, key, u64, flags)
{
struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
struct sock *sk;
if (unlikely(flags & ~(BPF_F_INGRESS)))
@ -667,8 +666,7 @@ BPF_CALL_4(bpf_sk_redirect_map, struct sk_buff *, skb,
if (unlikely(!sk || !sock_map_redirect_allowed(sk)))
return SK_DROP;
tcb->bpf.flags = flags;
tcb->bpf.sk_redir = sk;
skb_bpf_set_redir(skb, sk, flags & BPF_F_INGRESS);
return SK_PASS;
}
@ -1250,7 +1248,6 @@ const struct bpf_func_proto bpf_sock_hash_update_proto = {
BPF_CALL_4(bpf_sk_redirect_hash, struct sk_buff *, skb,
struct bpf_map *, map, void *, key, u64, flags)
{
struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
struct sock *sk;
if (unlikely(flags & ~(BPF_F_INGRESS)))
@ -1260,8 +1257,7 @@ BPF_CALL_4(bpf_sk_redirect_hash, struct sk_buff *, skb,
if (unlikely(!sk || !sock_map_redirect_allowed(sk)))
return SK_DROP;
tcb->bpf.flags = flags;
tcb->bpf.sk_redir = sk;
skb_bpf_set_redir(skb, sk, flags & BPF_F_INGRESS);
return SK_PASS;
}